1. Field of the Invention
The present invention relates generally to a method for collecting residual gases in fuel filling plants and in fuel tanks, and an apparatus therefor. The term tank,is intended to cover both mobile and fixed tanks. More particularly, the present invention relates both to filling operations for vehicles and other thermal engines, and to tanks used for containing fuel in refineries and storage plants, including vehicle fuel carriers and the like.
2. Description of Related Art
During filling operations of liquid fuel such as for example petrol, diesel and the like, a part of the fuel passes from a liquid to a gassy state.
Inhalation of these gases is known to be damaging both to humans and the environment.
For these reasons such gases should advantageously be eliminated or at least limited as much as possible. Legislative steps have been taken which recognize the danger caused by such fumes with regard to operators working in the vicinity thereof, as well as for users and the environment. Indeed, there are already norms in force both in Italy and abroad which attempt to limit or eliminate the above-mentioned emissions in fuel refilling plants.
With reference to the specific case of fuel distribution plants, an attempt at a solution to the problems outlined provides fuel distributors wherein the dispensing pistol is provided with a sort of sucker terminal which achieves a seal between the pistol and the mouth of the filling conduit on the vehicle. The fuel dispensing pipe is coupled coaxially to a second pipe connected to a suction pump, which latter aspirates the gas and discharges same into a conduit leading to the underground fuel tank. This type of process contains at least two drawbacks.
A first of these relates to environmental safeguarding and is connected to the fact that the use of the fuel storage tank for the collection of the gases means that those very gases are released into the environment on each refilling operation of said tank. Thus the gases reach the environment eventually anyway.
A second drawback relates to the expense of the work needed to adapt existing fuel filling plants to this method. For each distributor a gas aspiration pump must be connected up to one of the filling station underground tanks, and these are often situated at a considerable distance from the distributor, leading to extensive excavation, refilling and recovering work.
The problem of gaseous residues is of considerable importance in relation to the transport of fuels and refilling of the tankers in refineries. Indeed, after having emptied their load into fuel station tanks, the tankers are full of residual gases. This in effect means that the same tankers, once empty, represent a real danger of explosion.
From an environmental point of view, a further negative characteristic of the present method of utilization of vehicle fuel tankers is connected with the exchange of fuel between said tanker trucks and the fixed tanks found in refineries (or intermediate fuel storage plants). In this case the gaseous residues are collected in storage tanks and burned off. The resulting candle-like flame is a familiar sight in refineries, but burning off also contributes to enviromental pollution.
Accordingly, it has been considered desirable to develop a new and improved method of recovery gasses which would overcome the foregoing difficulties and others while providing better and more advantageous overall results.